A pear tree orchard needn't be rigid rows of pear trees and grass. Consider underplanting pear trees with beneficial plants. Companion planting organically addresses special problems pear trees face. By setting specific plants beneath or near pear trees, you may substantially reduce the need for irrigation, fertilizer and pesticides. In turn, pear trees may benefit other crops. Best of all, companion planting is completely organic.
Proponents of companion planting believe that by growing certain plants together, they can either enhance the growth of their main crop or achieve a balance that benefits all of the plants. For example, the classic "three sisters" method combines corn, winter squash and beans in the same garden plot. The squash's large, prickly leaves suppress weeds while discouraging raccoons from raiding the corn stalks. The corn provides a natural trellis on which the beans grow. The beans add nitrogen to the soil, upon which both corn and squash feed heavily.
Attracting the "good" bugs that eat the "bad" bags that attack pear trees is key to beneficial companion planting. The Umbelliferae family of herbs and weeds, including dill, Queen Anne's lace, lovage, chervil and fennel, encourages the presence of the beneficial insects known as parasitic wasps. These wasps feed on the green fruit worm and codling moths, which can cause serious damage to pear and other fruit trees. Some companion plants provide pest protection by acting as alternate food sources. Nasturtiums represent a classic "trap crop." They attract aphids to their own flowers, rather than to the pear trees.
Seeding a pear orchard with white or red clover benefits the pear trees in several ways. The clover, one of many legume crops, adds nitrogen to the soil. The flowers attract pollinators. As "living mulch," clover also prevents soil erosion, suppresses weeds and retains moisture. If your trees tend to send up too much early growth, consider an alternative ground cover. Early growth, a consequence of excessive nitrogen in the soil, makes the pear trees vulnerable to the damaging disease known as fire blight. Use non-legume ground covers like grass or annual rye, buckwheat or oats, in areas in which excess nitrogen is a concern.
While it may seem obvious to seasoned orchardists, the most important companion plant for a pear tree is another pear tree. Few pear species will bear fruit without a different species to provide cross-pollination. Most European and Asian pears pollinate one another, but check with your nursery to ensure you're planting the right pear trees together. In the spring, the pear trees' flowers act as pollinators. Help the cross-pollination process along by underplanting the trees with additional plants which attract pollinating bees and butterflies, such as borage, calendula and goldenrod.
Benefits to Other Plants
Just as many plants provide beneficial qualities to pear trees, the trees themselves can act as "nurse crops" to other plants. Several annual food crops, including lettuce, spinach, sorrel and broccoli, thrive under full sun in the early spring, but tend to bolt if not given shade at the height of summer. Planting vegetables between pear trees enables these crops to get the light they need when the trees' branches are bare, yet the shade they crave as temperatures heat up and the trees leaf out and produce flowers and fruit.